The invention relates generally to a system for restraining a vehicle adjacent a loading dock, and more specifically to a wheel-actuated vehicle chocking device.
In the loading and unloading of vehicles at a loading dock, heavy equipment such as forklifts pass into and out of the vehicle to facilitate and expedite the unloading and/or loading of the vehicle. Accordingly, it is imperative that the vehicle remain in a fixed abutting relationship relative to the loading dock to prevent accidents, and to protect the safety of dock personnel. Without such securement, there is a potential hazard that the vehicle could be inadvertently moved away from the loading dock during the loading/unloading operation. If this were to occur without the knowledge of the dock personnel, they could continue to attempt to move cargo into or out of the vehicle assuming the presence of the vehicle at the dock, and injury to personnel or damage to dock equipment could occur.
Previous attempts to employ roadway positioned restraints to prevent the vehicle from prematurely moving away from the loading dock have been largely unsuccessful, or have several shortcomings. Attempts to place wheel blocks underneath and wedged in front of the vehicles"" wheels have been unsuccessful because 1) the blocks are easily lost or damaged; 2) the blocks may not operate effectively due to a slippery road surface from oil, rain, ice, or snow; 3) the blocks are awkward to handle and sometimes difficult to remove from the wedged position; and 4) the blocks require the dock personnel manipulating the devices to be located on the roadway adjacent the dock requiring care to be exercised to avoid being injured by the vehicle.
Given the potential hazards of such manual placement of wheel chocks, automated chocking systems have been employed. While such systems are safer and more convenient than manual positioning of chocks, they may have their own disadvantages. For example, such systems may be incapable of being utilized with a wide variety of vehicle designs because they may interfere with the vehicle undercarriage, tailgate lifts, mud flaps or adjacent tires as they move into an engaging position with the wheel. In addition, such systems may not be adjustable to accommodate the large range of tire sizes on cargo vehicles. Such systems may also be awkward, difficult and time consuming to engage and disengage from the vehicle parked at the dock.
In the co-pending application Ser. No. 08/327,308 filed on Oct. 21, 1994, the priority benefit of which is hereby claimed, and which is assigned to the assignee of the present invention, a vehicle restraint was disclosed which avoided many of the shortcomings in the art. The wheel-activated restraint disclosed therein is actuated and positioned by the vehicle itself, and includes the feature of automatically adjusting to accommodate various sizes of tires. The invention disclosed herein represents improvements and enhancements to the design disclosed in application Ser. No. 08/327,308, the contents of which are expressly incorporated herein by reference.
Throughout this specification, the term xe2x80x9cdockxe2x80x9d or xe2x80x9cloading dockxe2x80x9d will be used to broadly refer to loading stations of all kinds, including raised loading docks, where positive and safe positioning of a vehicle is desired. Further, the vehicle may approach the loading dock over a variety of vehicle supporting surfaces. Herein, the vehicle will be described as approaching the dock over a xe2x80x9croadwayxe2x80x9d. This term is meant to broadly encompass vehicle support surfaces of every kind including roads, driveways, ramps, bridges, pits, truck leveler surfaces, and the like.
It is a primary aim of the invention to enhance and improve upon the restraint disclosed in prior U.S. application Ser. No. 08/327,308.
In accordance with that aim, it is a primary object of the invention to provide a restraint device which is capable of accommodating vehicles of widely varying configurations and tire sizes.
A further object of the invention is to provide a restraint device which is compact and has a low profile for accommodating vehicles having low undercarriages or low tailgates.
It is a related object to provide a restraint with a low profile relative to the roadway such that, during actuation, the restraint does not interfere with any other portion of the vehicle beside the tire, i.e. ICC bars, tailgates, fenders, or mud flaps, thus insuring that the restraint properly contacts and restrains the tire.
It is a further object to provide a restraint that can accommodate itself to variations in height in the roadway surface while still maintaining adequate contact with both the roadway surface, and with the tire being engaged.
A further object of the invention is to provide a restraint that can be easily and effectively latched into place relative to the loading dock once the vehicle tire is chocked.
It is a related object of the invention to provide a latching system that can readily accommodate pullout forces exerted thereon by the docked and chocked vehicle.
It is a further related object that such pullout forces not be borne by the drive mechanism by which the system is initially latched.
A further object is to provide a restraint system including a visual or other indication of securement of the vehicle in the loading/unloading position.
A still further object of the invention is to provide a restraint system including the feature of guiding the vehicle into position relative to the restraint, so that proper activation and engagement of the tire is carried out.
In accordance with these and other objects of the invention, there is provided a wheel-activated vehicle restraint system for at least one wheel of the vehicle which restrains the vehicle at a loading/unloading position adjacent the dock. According to the preferred embodiment of the invention, the restraint includes a support structure disposed beside the path of the vehicle approaching the dock. The support structure includes a guide member extending away from the dock face, and a supporting member disposed above the guide member. A trigger assembly is operatively connected to the guide member, and initially engages the wheel of the vehicle as it rolls toward the dock. The restraint also includes a locking arm which operatively engages the supporting member to move from a stored position to a chocking position on the wheel as the wheel engages the trigger and moves it toward the dock. To provide such movement of the locking arm in response to movement of the trigger by the wheel, a trolley assembly operatively connects the trigger assembly and the locking arm, the trolley assembly and the locking arm being connected at a connection point. According to the invention, the trigger assembly is selectively positionable relative to the connection point in response to the dimensions of the wheel. As a result, the locking arm engages a bottom portion of the wheel, and moves along the peripheral surface of the wheel to a chocking position as the wheel continues to push the trigger assembly toward the dock. The movement of the locking arm along the peripheral surface of the tire minimizes or eliminates any interference between the vehicle undercarriage and the restraint.
In a preferred embodiment of the invention, the trolley assembly is connected to the trigger assembly by resilient members illustratively in the form of springs. The trolley assembly and springs thus serve as a variable length biasing link allowing the trigger assembly to be selectively positionable relative to the connection point between the trolley assembly and locking arm. As the trigger assembly is moved in a dockward direction, this variable length biasing link resiliently biases the locking arm from the stored position toward the chocking position. Moreover, the wheel is properly sized by the restraint and the locking arm traces out its advantageous pathxe2x80x94first engaging a bottom portion of the wheel, and then moving along a peripheral surface of the wheel to the chocking position.
According to a further aspect of the invention, an operator actuated latching mechanism is provided to secure the vehicle in place adjacent the loading dock with the locking arm in the chocking position. An actuator is operatively connected to the latching bar for moving a latch member between a non-engaging and an engaging position. In the engaging position, a textured engaging portion of the latch member engages an upper surface of the guide member, while the engaging portion is spaced from the surface when it is in the non-engaging position. According to the preferred embodiment, engagement blocks are disposed on the trolley assembly such that the movement of the latch member to the engaging position causes the guide member to be clamped between the engaging portion and the engaging block. Advantageously, the structure of the latch mechanism is such that, as a pullout force is exerted on the restraint, the clamping force increases, and the latch member decouples from the latching bar, thus preventing the pullout force from being transferred to the actuator.
According to a further aspect of the invention, the latch mechanism also includes a sensor for sensing the movement of the latching bar between unlatched and latching positions. A first signal is generated when the latching bar moves to the latching position, and such signal may illuminate a visual indicator. The visual indicator signals dock personnel that the unloading/loading operation may be safely performed and/or signals the vehicle operator not to attempt to pull away. In addition, a second sensor may sense movement of the locking arm to the chocking position. A visual indicator that illuminates in response to signals from both the first and second sensors ensures not only that the latching mechanism is actuated, but also that the vehicle wheel is properly chocked.